1. Risk of bias assessment.

Trial	Allocation sequence generation	Allocation concealment	Blinding	Inclusiona
Anabwani 1999	Unclear	Unclear	None	Adequate
Borrmann 2003	Adequate	Adequate	None	Inadequate
Bouchaud 2000	Unclear	Unclear	None	Inadequate
De Alencar 1997	Unclear	Unclear	None	Inadequate
Giao 2004	Adequate	Adequate	None	Adequate
Llanos‐Cuentas 2001	Unclear	Unclear	None	Adequate
Looareesuwan 1999a	Unclear	Unclear	None	Inadequate
Mulenga 1999	Unclear	Unclear	None	Adequate
Radloff 1996	Adequate	Unclear	None	Inadequate
Van Vugt 2002	Adequate	Adequate	None	Adequate

^aSee the 'Characteristics of included studies' for details.
 ^bInclusion of all randomized participants in the final analysis.